Research on the Behaviour, Nature and Meaning of the Rheumatoid Factor

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Abstract
Summary The authors have performed 3,050 determinations of the W.R. test, as modified by Heller, on 1,643 subjects 511 of whom were R.A. patients; the remaining 1,132 were partly normal subjects and partly patients affected by rheumatic and non-rheumatic diseases different from R.A. The W.R. test was found positive with various titres in 63.9 % of the cases of R.A. The different clinical, radiological and therapeutical factors which might influence the result of the test, are discussed. In individuals not affected by R.A. the W.R. test was almost constantly negative; The test was positive, generally with a rather low titre, in 8.4 % of the cases of rheumatic fever, in 8.8 % of the cases of ankylosing spondylitis, in 14.3 % of the cases of arthropathy with psoriasis, in 8.8 % of the cases of gout, in 10.8 % of the cases of secondary rheumatism, in none of the cases of scleroderma and dermatomyositis, in 0.63 % of the controls (arthrosis and healthy subjects), in 8.7 % of the cases of silicosis, in 2.1 % of the cases with different non-rheumatic diseases. Only in lupus erythematosus disseminatus was positivity frequent (5 cases out of 10). In the relatives of R.A. patients the agglutination titre showed a slight but relatively frequent increase (in 32.1 % of relatives of Rose-positive R.A. patients). In the joint exudative fluid and in the fluid of the tissues of R.A. patients the rheumatoid factor was found in concentrations similar to those found in the serum. A comparison between the W.R. test and the drop latex test, carried out in 499 cases, proved the existence of a noticeable parallelism between the results of the two tests; in the cases of R.A. the drop latex test shows a slightly higher sensitivity with lower specificity. The drop latex test, performed by means of the standard technique, does not seem to be useful for finding the rheumatoid factor in the joint exudative fluid, since the test is there almost always positive, independently of the nature of the arthropathy and of the result of the reaction in the blood serum. The authors discuss the practical importance of looking for the agglutinating factor in regard to the early diagnosis, to the differential diagnosis and to the nosography of the rheumatic diseases and underline the theoretical interest of such serological investigations for the study of the etiopathogenesis of R.A. They finally report on the results of a series of personal researches, aiming at defining the significance and nature of the agglutinating factor, which is characteristic of rheumatoid arthritis.